The present invention relates to oil and gas well drilling equipment and, more particularly, to improvements in power-operated drill pipe spinners and an improved combination of a power-operated drill pipe spinner and conventional drill pipe tongs for making up and breaking out sections of drill pipe.
A search of the prior art failed to uncover any prior art reference which discloses the drill pipe spinner apparatus of the present invention. A number of prior art patents were uncovered which disclose power-operated spinners for making up and breaking out drill pipe as exemplified by the following patents:
U.S. Pat. No. 1,925,970 PA1 U.S. Pat. No. 2,649,283 PA1 U.S. Pat. No. 2,703,221 PA1 U.S. Pat. No. 2,746,329 PA1 U.S. Pat. No. 2,862,690 PA1 U.S. Pat. No. 2,871,743 PA1 U.S. Pat. No. 3,021,739 PA1 U.S. Pat. No. 3,041,901 PA1 U.S. Pat. No. 3,086,413 PA1 U.S. Pat. No. 3,799,009 PA1 U.S. Pat. No. 3,906,820
Generally, one of the main advantages of known power-operated drill pipe spinners is that the practice of using the extremely dangerous spinning line or chain for making up and breaking out drill pipe sections is eliminated, as well as the requirement for two workmen on the drilling rig floor. Despite the danger of this practice and the availability of power spinner equipment, some drilling operations are still carried out using a spinning chain because of the typically high cost of power-operated spinning equipment and, in the case of some known power spinners, the inability of the equipment to develop the torque necessary for making up or breaking out the drill string, especially when the drill pipe is dirt or oil-coated. When insufficient torque is available, it becomes necessary for the drilling floor crew to effect final make-up torque using conventional pipe tongs, which obviously results in inefficient drilling operations.
U.S. Pat. No. 3,086,413, listed above, discloses a power-driven spinner adapted to be mounted on any conventional, manually operable drill pipe tongs. According to this patent, the tongs are mounted to the power-driven spinner by means of a rather complex arrangement of parts connected to a heavy pin inserted in a bore formed in the lever arm of the tongs. After a length of tubing is spun into threaded engagement with the drill string, the jaws of the tongs are manually pivoted to a closed and locked or tube-gripping position so that torque of a desired magnitude can be applied to the tongs to effect final make-up of the tubing to the drill string. A disadvantage of this arrangement is that, after the initial spinning of the tubing to effect threaded engagement of the joint, the spinner operator or floorman must manually close and lock the tongs in gripping engagement with the tubing so as to permit final torquing. This procedure is not only inefficient in that it wastes valuable time during running-in or breaking-out of the drill string, but also requires a floorman to return to the area of the drill string during these operations to perform the required and inherently dangerous manual manipulation of the tongs.
In U. S. Pat. No. 3,906,820 mentioned above, there is disclosed a power spinner which employs a flexible drive element comprising a so-called "silent chain" for grippingly engaging the tubing. As shown and described in this patent, the term "silent chain" defines an inverted-tooth chain made up of a plurality of interleaved planar leaf links which may be constructed in accordance with American Society of Automotive Engineers Standard B29.2. The use of silent chain in a power spinner, as disclosed in this patent, enables the development of large gripping forces on the pipe to be spun. In this known power spinner apparatus, a single endless silent chain is trained about a drive sprocket, the drill pipe and two pair of sprocket wheels, each sprocket wheel pair being associated with a respective pipe gripping jaw. One disadvantage of this arrangement is that the length of the endless silent chain required for the operation of the apparatus is quite long and, in view of the high cost per foot of this chain, very expensive to replace when the same is broken or otherwise removed for repair or the like.